Cavellino Bianco in Ortisei is exceptionally good, we were there last week. This is in the Dolomites, beautiful village and 1 min to the cable car for some gentle walking (as little as 20 minutes if you choose) across to a (kid friendly) mountain hut for lunch.

Currently in Croatia at the new Family Resort Amarin in Rovinij. This really is a kids paradise but almost too much - you are stuck sitting by the pool. Very expensive but all inclusive. Cavellino is classier, probably because the mountains attract a healthy crowd.